JP2007294399A - Rare gas fluorescent lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain homogeneity of brightness distribution of a tube axial direction, suppress flickering, and prevent generation of a surge voltage of a lamp voltage in a frequency increase period, even if a rare gas fluorescent lamp is dimmed by burst light adjustment. <P>SOLUTION: In the rare gas fluorescent lamp lighting device which is provided with a rare gas fluorescent lamp 1, and an inverter circuit 100 to apply an alternate current high voltage to a lamp 1, the circuit 100 is composed of an inverter control circuit 102 to output a switching element operation signal, a switching element circuit 101 to convert a direct current voltage into an alternate current voltage by turning on and off controlling the switching element according to the switching element operation signal, and a transformer 111 to boost voltage of the alternate current voltage from the circuit 101, and in which the burst light adjustment is carried out by controlling time ratio of a light-on period and a light-off period of the lamp 1, in a period from a lighting start point of the burst light adjustment to the whole light emission completion point in which the lamp 1 emits light over the whole in the approximately axial direction, a frequency of the switching element operation signal of at least one part of the period is made to be higher than the frequency of the switching element operation signal at a stationary time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rare gas fluorescent lamp lighting device used for backlight, illumination, and the like of a liquid crystal display panel.

  Cold cathode fluorescent lamps and hot cathode fluorescent lamps are often used as backlight light sources and illumination lamps for liquid crystal display panels. These lamps contain a very small amount of mercury inside, and emit phosphors by ultraviolet rays generated from mercury excited by discharge, so that high-luminance and efficient light emission can be obtained. Are better.

  However, a new light source that does not contain mercury is desired from the viewpoint of preventing environmental pollution. As a fluorescent lamp that does not contain mercury, a plurality of strip-like electrodes are arranged on the outer surface of a glass tube, and a high-frequency high voltage boosted by, for example, a step-up transformer is applied to these electrodes to turn on a rare gas. Fluorescent lamps have been proposed. In such a rare gas fluorescent lamp, for example, as shown in Patent Document 1, an easy start to assist the start of the rare gas fluorescent lamp, such as applying a conductive material to the inside of the glass tube end portion. A site is formed.

  Further, in an external electrode type rare gas fluorescent lamp that is lit by applying a high-frequency high voltage, as shown in Patent Document 2, the lamp voltage waveform applied to the electrode is not a sine wave voltage but a rectangular shape. Luminous efficiency is enhanced by applying a voltage including a steep voltage change such as a wave voltage.

In general, the screen brightness of a liquid crystal display panel equipped with such a rare gas fluorescent lamp can be adjusted to an appropriate size according to ambient brightness, user preference, image information, and the like. The screen brightness is adjusted by dimming the backlight. The backlight dimming is generally burst dimming. Also in lighting applications, a wide light control range is required in order to adjust the brightness according to the usage environment in indirect lighting or the like. As a method, burst dimming is generally used in the same manner as the backlight. Burst dimming is also called duty dimming. For example, the lamp lighting period and the extinguishing period are repeated at a cycle of 60 Hz or more, and the lighting period and the extinguishing period are periodically repeated at about 60 to 1 kHz. The light is adjusted by controlling the time ratio of the period. The dimming period is appropriately selected from about 60 to 300 Hz for a liquid crystal backlight and about 1 kHz for lighting applications. These periods are selected by a period that is not perceived by human eyes, and the periods are not specified in the above-described range.
Japanese Patent No. 3149780 JP-A-6-163008

A case where burst dimming of the rare gas fluorescent lamp 1 will be described with reference to FIG. The figure shows a burst dimming signal, a light output at a measurement point A, and a light output at a measurement point B.
In the rare gas fluorescent lamp 1 provided with the easy start part 15, measurement is performed when burst light control lighting is performed with the vicinity of the easy start part 15 as the measurement point A and the place away from the easy start part 15 as the measurement point B. The light output at point A and measurement point B was measured. At the beginning of the lighting period, light emission immediately started at measurement point A, but light emission started at measurement point B later than that.

The reason why the light emission at the measurement point B is emitted later than the measurement point A is considered as follows. The discharge of the rare gas fluorescent lamp 1 repeats a discharge cycle that occurs at the moment when a steep voltage change occurs when the polarity of the applied voltage is reversed and stops until the next steep voltage change. Further, the rare gas fluorescent lamp 1 is likely to be discharged due to the accumulation of electric charges on the inner surface of the glass tube 11 corresponding to the place where the electrode is disposed. At the beginning of the lighting period, first, the starting point of the discharge is generated at the easy start portion 15, but since the charge accumulated on the inner surface of the glass tube 11 during the extinguishing period has almost disappeared, the discharge is performed with the rare gas fluorescent lamp 1. It does not spread over the entire area and occurs only around the easily startable portion 15. In the region where the discharge has occurred, charges are accumulated on the inner surface of the glass tube 11, so that the discharge is easily generated in the next discharge cycle, and this is the starting point, and further, a discharge is generated in the vicinity thereof. As described above, the discharge spreads over the entire rare gas fluorescent lamp 1 by repeating the discharge cycle several times. The time required to repeat this discharge cycle is a delay in light emission at the measurement point B.
In addition, since the discharge is not sufficiently formed at the beginning of the lighting period, the capacitance component of the rare gas fluorescent lamp 1 is reduced. Since the flat part of the lamp voltage waveform can be regarded as a part of the resonance waveform of the inductance and capacitance component of the transformer connected to the lamp, when the capacitance component of the rare gas fluorescent lamp 1 is small, the flat part has a large attenuation. It becomes a waveform. As a result, the magnitude of the steep voltage change when the polarity is switched is reduced, and the energy supplied to the rare gas fluorescent lamp 1 is reduced, so that the emission delay at the measurement point B is increased.

  For this reason, it takes time for the discharge generated in the easy-start portion 15 to spread in the entire axial direction of the rare gas fluorescent lamp 1 at the beginning of the lighting period within the burst dimming period. Accordingly, as shown in FIG. 14, light emission starts immediately at the measurement point A at the beginning of the lighting period, but light emission starts later than that at the measurement point B. On the other hand, since the discharge of the entire rare gas fluorescent lamp 1 stops almost simultaneously at the end of the lighting period, the light emission at the measurement points A and B stops simultaneously. Therefore, the light emission time at the measurement point B within the lighting period is shorter than the measurement point A by the light emission delay time, the brightness is lower than that at the measurement point A, and the luminance distribution in the axial direction of the rare gas fluorescent lamp 1. Deteriorates the uniformity. Further, the light emission delay time at the measurement point B varies within a range of about ± 40% with respect to the average value. For this reason, the brightness of the measurement point B changes every burst dimming cycle, and flickering occurs in the vicinity of the measurement point B.

  In view of the above problems, an object of the present invention is to maintain the uniformity of the luminance distribution in the axial direction of the rare gas fluorescent lamp and suppress flickering even if the rare gas fluorescent lamp is dimmed by burst dimming. The object is to provide a lamp lighting device.

The present invention employs the following means in order to solve the above problems.
The first means is that a glass tube is filled with one or more kinds of rare gases of He, Ar, Xe, and Kr, a phosphor is applied to the inner surface of the glass tube, and extends in the axial direction of the glass tube. A rare gas fluorescent lamp provided with an electrode, and an inverter circuit for applying an alternating high voltage to the electrode, the inverter circuit including an inverter control circuit for outputting a switching element operation signal, and the switching element operation signal A switching element circuit that converts a DC voltage into an AC voltage by controlling on and off according to the switching element, and a step-up transformer that boosts the AC voltage from the switching element circuit. A rare gas fluorescent lamp lighting device that performs burst dimming by periodically repeating the period and controlling the time ratio between the lighting period and the extinguishing period The frequency of the switching element operation signal in at least a part of the period from the start of lighting of the burst dimming to the end of the total emission in which the rare gas fluorescent lamp emits light substantially in the entire axial direction is The noble gas fluorescent lamp lighting device is characterized in that the frequency is higher than the frequency of the switching element operation signal.
A second means is the rare gas fluorescent lamp lighting device according to the first means, wherein the frequency of the switching element operation signal is gradually increased in the initial period of the at least part of the period.
According to a third means, in the first means or the second means, at least within a period from a lighting start time of the burst dimming to a time point when the noble gas fluorescent lamp emits light substantially in the entire axial direction. The frequency of the switching element operation signal is continuously changed when returning from the frequency of the switching element operation signal in a part of the period to the frequency of the switching element operation signal in the steady state. This is a gas fluorescent lamp lighting device.
The fourth means is that a glass tube is filled with one or more kinds of rare gases of He, Ar, Xe, and Kr, a phosphor is applied to the inner surface of the glass tube, and extends in the axial direction of the glass tube. A rare gas fluorescent lamp provided with an electrode, and an inverter circuit for applying an alternating high voltage to the electrode, the inverter circuit including an inverter control circuit for outputting a switching element operation signal, and the switching element operation signal A switching element circuit that converts a DC voltage into an AC voltage by controlling on and off according to the switching element, and a step-up transformer that boosts the AC voltage from the switching element circuit. A rare gas fluorescent lamp lighting device that performs burst dimming by periodically repeating the period and controlling the time ratio between the lighting period and the extinguishing period The duty ratio of the switching element operation signal in at least a part of the period from the start of lighting of burst dimming to the completion of all light emission in which the rare gas fluorescent lamp emits light in the entire axial direction is determined. A rare gas fluorescent lamp lighting device characterized by having a duty ratio higher than that of the switching element operation signal at all times.
A fifth means is the rare gas fluorescent lamp lighting device according to the fourth means, wherein the duty ratio of the switching element operation signal is gradually increased at the beginning of the at least part of the period.
A sixth means is the fourth means or the fifth means according to the fourth means or the fifth means, at least in a period from a start time of the burst dimming to a complete light emission time when the rare gas fluorescent lamp emits light in the entire axial direction. When returning from the duty ratio of the switching element operation signal during a part of the period to the duty ratio of the switching element operation signal in the steady state, the duty ratio of the switching element operation signal is continuously changed. And a rare gas fluorescent lamp lighting device.
The seventh means is that a glass tube is filled with one or more kinds of rare gases of He, Ar, Xe, and Kr, a phosphor is applied to the inner surface of the glass tube, and extends in the axial direction of the glass tube. A rare gas fluorescent lamp provided with an electrode, and an inverter circuit for applying an alternating high voltage to the electrode, the inverter circuit including an inverter control circuit for outputting a switching element operation signal, and the switching element operation signal A switching element circuit that converts a DC voltage into an AC voltage by controlling on and off according to the switching element, and a step-up transformer that boosts the AC voltage from the switching element circuit. A rare gas fluorescent lamp lighting device that performs burst dimming by periodically repeating the period and controlling the time ratio between the lighting period and the extinguishing period The frequency and duty ratio of the switching element operation signal in at least a part of the period from the start of lighting of burst dimming to the completion of all emission in which the rare gas fluorescent lamp emits light substantially in the entire axial direction. A rare gas fluorescent lamp lighting device characterized in that it is higher than the frequency and duty ratio of the switching element operation signal in a steady state.
The eighth means is the seventh means according to the seventh aspect, wherein at least a part of a period from a start time of the burst dimming to a complete light emission time when the rare gas fluorescent lamp emits light substantially in the entire axial direction. When returning from the frequency and duty ratio of the switching element operation signal to the frequency and duty ratio of the switching element operation signal in the steady state, continuously changing the magnitude of the frequency and duty ratio of the switching element operation signal. This is a rare gas fluorescent lamp lighting device.

According to the present invention, by increasing the frequency of the switching element operation signal or the duty ratio, it is possible to accelerate the spread of the discharge in the entire axial direction of the rare gas fluorescent lamp. As a result, it is possible to suppress a delay in light emission at a location away from the easily startable portion, and maintain the uniformity of the luminance distribution in the axial direction of the rare gas fluorescent lamp. Further, by suppressing the delay of the light emission, the change in brightness due to the variation in the delay time is reduced, and the flicker that occurs at a place away from the easily startable portion can be suppressed.
In addition, when the switching element operating signal frequency and duty ratio transition from a high period to a steady operating period, the switching element operating signal frequency and duty ratio magnitude change continuously and gradually, not discontinuously. By doing so, the voltage waveform of the rare gas fluorescent lamp is not disturbed, and the discharge can be prevented from becoming unstable.
Further, by suppressing a high surge voltage generated during a period when the frequency and duty ratio of the switching element operation signal are high, it is possible to provide a rare gas fluorescent lamp lighting device that is excellent in terms of safety.

  The present invention will be described below with reference to FIG. FIG. 1 is a diagram showing a basic configuration of a rare gas fluorescent lamp lighting device that performs burst dimming according to the present invention.

  In the rare gas fluorescent lamp lighting device, as shown in FIG. 1, a DC voltage of several tens to several hundreds V supplied from a DC power source 114 is an AC high voltage of several tens of kHz and several kV by an inverter circuit 100. Is converted to This alternating high voltage is applied to the external electrodes 12 and 13 extending in the axial direction of the outer surface of the glass tube 11 of the rare gas fluorescent lamp 1 shown in FIG. As shown in FIG. 3 (b), the rare gas fluorescent lamp 1 is a straight tubular envelope that is hermetically sealed with a glass tube 11, and an external electrode 12 extending in the axial direction is formed on the outer surface of the envelope. 13 is arranged, a fluorescent material is formed on the inner surface, and a predetermined amount of a rare gas mainly containing one or more of He, Ar, Xe, and Kr is sealed. In addition, at least one easy-start portion 15 is disposed inside the glass tube 11.

  The inverter circuit 100 is a circuit that converts a DC voltage into an AC high voltage and outputs it, and includes an inverter control circuit 102, a switching element circuit 101, and a step-up transformer 111. The inverter control circuit 102 outputs a switching element operation signal 103. The switching element operation signal 103 is a periodic pulse signal for ON / OFF control of the switching element of the switching element circuit 101. The switching element circuit 101 is configured by a push-pull circuit method, a half-bridge circuit method, a full-bridge circuit method, and the like. Convert to AC voltage. This AC voltage is boosted by the step-up transformer 111 and becomes an output voltage of the inverter circuit 100. Burst dimming is performed by intermittently operating the inverter circuit 100 in accordance with the burst dimming signal 113.

With respect to such a rare gas fluorescent lamp lighting device, a first embodiment of the present invention will be described with reference to FIGS.
2 is a diagram showing a configuration of a rare gas fluorescent lamp lighting device that performs burst dimming according to the present invention, FIG. 3 is a diagram showing a configuration of the rare gas fluorescent lamp 1 shown in FIG. 2, and FIG. FIG. 5 is a diagram showing a configuration in which the rare gas fluorescent lamp 1 shown in FIG. 2 is used as a backlight of a liquid crystal panel, FIG. 5 is a diagram showing the relationship between the frequency of the switching element operation signal 103 and the relative value of luminous efficiency, and FIG. FIG. 4 is a diagram illustrating an operation waveform and a lamp voltage waveform 112 representing ON and OFF states of a burst dimming signal 113, a switching element operation signal 103, and switching elements Q1 and Q2.

A rare gas fluorescent lamp 1 shown in FIG. 3 is, for example, a straight tube envelope that is hermetically sealed with a glass tube 11, and fluorescent light such as a rare earth phosphor or a halophosphate phosphor is formed on the inner surface thereof. A fluorescent substance 14 made of a body is formed. The sealing structure of the glass tube 11 is configured by sealing a disc-shaped sealing glass plate to the end of the glass tube 11. For example, the glass tube 11 is simply heated while the glass tube 11 is heated and melted. It can also be constituted by a top seal. The external electrodes 12 and 13 are configured, for example, by cutting an aluminum tape into a width of 1 mm and pasting it on the outer surface of the glass tube 11 at a position facing the central axis of the rare gas fluorescent lamp 1. The external electrodes 12 and 13 may be formed by screen printing and baking a conductive paste, for example.
The sealed space of the glass tube 11 is filled with a predetermined amount of a rare gas whose main component is at least one of He, Ar, Xe, and Kr that does not contain metal vapor such as mercury.

  The easily startable portion 15 is made of a conductive material or an easily electron emitting material, and is disposed at least one place inside the glass tube 11 in order to facilitate the start of discharge. Discharge occurs from the easily startable portion 15 and spreads throughout the rare gas fluorescent lamp 1 from there. Usually, it is provided at the end of the glass tube 11 so as not to affect the light extraction efficiency during lighting.

As the conductive material, a material containing one or more of silver, aluminum, graphite, tin oxide, indium oxide, barium, nickel, or the like as a material, or a mixed material of the material and a binder can be used as appropriate. . As the material for the electron-emitting material, a material containing one or more of carbon nanotubes, magnesium oxide, cesium oxide, aluminum oxide, zinc oxide, lead oxide or the like, or a mixed material of the above-mentioned material and a binder is appropriately used. be able to. Further, the shape is not particularly limited, and a dot shape, a granular shape, a square shape, or a belt shape can be used as appropriate. Furthermore, it is not limited to providing one place at the end of the glass tube 11, and it is possible to provide a plurality of places. In the meaning of improving the starting characteristics, it is also possible to arrange the easily startable portion 15 in a portion other than the end. Is possible enough.
In addition, the easily startable portion 15 is, for example, fixed by baking at 400 ° C. after being applied to the glass tube 11, and as a method for providing, a method of directly welding to a glass material on the inner surface of the glass tube 11, a method by application, Adhesion with an adhesive or the like can be employed.

  Moreover, the easy start part 15 can provide a constriction part in a part of discharge space, and can also improve lighting start property from this. Further, the narrowed portion can be formed by forming a protrusion inwardly in the glass tube 11. When discharging through the discharge space between the external electrodes 12 and 13, the starting characteristics can be improved by designing a part of the discharge space at a short distance from the other part. Further, the narrowed portion is not limited to being provided at one end at the end of the glass tube 11, but can be provided at a plurality of locations or at portions other than the end.

  As shown in FIG. 4, the rare gas fluorescent lamp 1 has an opening on one plane, and a plurality of substantially equal intervals are provided at the bottom of a metallic casing 19 having a diffuse reflection sheet such as foamed PET disposed on the inner surface. Is arranged in. A diffusion plate 18, an optical film 17, and a liquid crystal panel 16 are stacked in this order in the light irradiation direction in the opening on the front side in the light irradiation direction of the housing 19. Here, as the material constituting the diffusion plate 18, the optical film 17, and the liquid crystal panel 16, those conventionally used suitably are used.

  In this rare gas fluorescent lamp lighting device, as shown in FIG. 2, the DC voltage supplied from the DC power supply 114 is converted into an AC high voltage by the inverter circuit 100 and supplied to the rare gas fluorescent lamp 1 as lighting power. Is done. Further, the inverter circuit 100 intermittently operates in accordance with the burst dimming signal 113 to perform burst dimming. The inverter circuit 100 includes a step-up transformer 111, a switching element circuit 101, and an inverter control circuit 102. More specifically, the switching element circuit 101 includes a switching element Q1, a switching element Q2, and a switching element driving circuit 2. The inverter control circuit 102 includes a comparator 4, a comparison voltage control circuit 5, an oscillation circuit 6, a frequency increase circuit 7, a delay circuit 8, and a timer circuit 9.

  First, the inverter control circuit 102 will be described. The oscillation circuit 6 in the inverter control circuit 102 outputs an oscillation signal having a periodic sawtooth waveform. The sawtooth waveform voltage is inputted to the plus terminal of the comparator 4, and the comparison voltage from the comparison voltage control circuit 5 is inputted to the minus terminal. Is entered. Only when the drive signal having the sawtooth voltage exceeds the comparison voltage, the output voltage of the comparator 4 becomes High. That is, the switching element operation signal 103 that becomes the output voltage of the comparator 4 has a pulse waveform whose duty ratio changes depending on the magnitude of the comparison voltage. The duty ratio increases as the comparison voltage decreases, and decreases as the comparison voltage increases. Become.

  When the burst dimming signal 113 is High, the transistor in the comparison voltage control circuit 5 is in an OFF state, and the comparison voltage input to the minus terminal of the comparator 4 is Vref × R2 / (R1 + R2). This comparison voltage Vref × R2 / (R1 + R2) is smaller than the peak voltage of the sawtooth waveform that is the oscillation signal of the oscillation circuit 6. Therefore, the comparator 4 outputs the switching element operation signal 103 which is a pulse waveform having a duty ratio corresponding to the magnitude of the comparison voltage, and turns on the rare gas fluorescent lamp 1. When the burst dimming signal 113 is Low, the transistors in the comparison voltage control circuit 5 are turned on, and the comparison voltage is almost the same as Vref. Since the magnitude of Vref is set larger than the peak voltage of the sawtooth waveform that is the oscillation signal of the oscillation circuit 6, the switching element operation signal 103 that is the pulse waveform output of the comparator 4 is stopped, and the rare gas fluorescent lamp 1 is Turns off.

  Further, the inverter control circuit 102 controls the timer circuit 9 for controlling the magnitude of the frequency increase period of the switching element operation signal 103, and changes the frequency of the switching element operation signal 103 from the end of the frequency increase period to the steady operation period through the transition period. A delay circuit 8 for continuously changing and a frequency increasing circuit 7 for temporarily decreasing the timing resistance of the oscillation circuit 6 and increasing the frequency are provided. The frequency of the oscillation circuit 6 is determined by the size of the timing resistor RT and the timing capacitor CT, and the timing resistor RT and the oscillation frequency are in an inversely proportional relationship. The burst dimming signal 113 is input to the comparison voltage control circuit 5 and the timer circuit 9.

  When the burst dimming signal 113 becomes High, the output of the timer circuit 9 becomes High at the same time as the transistor in the comparison voltage control circuit 5 is turned OFF. The capacitor of the delay circuit 8 is immediately charged and the transistor of the frequency increasing circuit 7 is turned on. As a result, the timing resistance of the oscillation circuit 6 becomes the magnitude of the parallel resistance of R4 and RT, and the operating frequency of the switching element operation signal 103 that is inversely proportional to the timing resistance value increases. Next, when the set time of the timer circuit 9 elapses, the output of the timer circuit 9 becomes Low. The set time of the timer circuit 9 is a size obtained by experiments in advance for the time required from the lighting start time of the burst dimming to the time when the rare gas fluorescent lamp 1 emits light almost in the entire axial direction. When the output of the timer circuit 9 becomes Low, the capacitor voltage of the delay circuit 8 gradually decreases according to the time constant of the capacitor and the resistance, the resistance between the collector and emitter of the transistor of the frequency increasing circuit 7 gradually increases, and the frequency is Decreases gradually continuously. When the transistor is completely turned off, the timing resistance becomes RT, so that the operating frequency of the switching element operation signal 103 returns to a steady magnitude. In this way, the transition period from the state in which the operating frequency of the switching element operation signal 103 increases to the time when the switching element operation signal 103 gradually decreases and returns to a steady magnitude is appropriately set according to the time constants of the capacitors and resistors constituting the delay circuit 8. .

  Subsequently, the switching element circuit 101 and the step-up transformer 111 will be described. The switching element operation signal 103 is input to the switching element drive circuit 2 in the switching element circuit 101. When the switching element operation signal 103 becomes High, the switching element drive circuit 2 turns on one of the switching elements Q1 and Q2. Subsequently, when the switching element operation signal 103 becomes Low, both the switching elements Q1 and Q2 are turned off. Subsequently, when the switching element operation signal 103 becomes High, the switching element that is not the switching element that was previously turned on is turned on. By repeating such a switching operation, the polarity of the voltage applied to the primary side of the step-up transformer 111 is periodically inverted, and an alternating high voltage is generated from the secondary side of the step-up transformer 111.

  The discharge of the rare gas fluorescent lamp 1 repeats a discharge cycle that occurs at the moment when a steep voltage change occurs when the polarity of the applied voltage is reversed and stops until the next steep voltage change. After the discharge starting point is generated at the easy start portion 15, it is necessary to repeat the discharge cycle a plurality of times in order to spread the discharge throughout. By increasing the frequency of the switching element operation signal 103, the number of discharge cycles per unit time can be increased, and the spread of discharge can be accelerated.

  As a result, it is possible to suppress a delay in light emission at a location away from the easy-to-start portion 15 and maintain the uniformity of the axial luminance distribution of the rare gas fluorescent lamp 1. Furthermore, since the delay in light emission is suppressed, the variation in the delay time is reduced. Therefore, the change in brightness due to variations in the delay time is reduced, and flickering that occurs at a location away from the easy-start portion 15 can be suppressed.

FIG. 5 is a diagram showing the relationship between the frequency of the switching element operation signal 103 and the relative luminous efficiency value of the rare gas fluorescent lamp 1.
As shown in the figure, since the luminous efficiency is maximized when the frequency of the switching element operation signal 103 is 100 kHz, the steady operation is preferably performed at around 100 kHz. When the frequency is increased, the frequency temporarily deviates from the high light emission efficiency. Therefore, if the state in which the frequency is increased is continued longer than necessary, the overall light emission efficiency is lowered. Therefore, the increase period of the frequency of the switching element operation signal 103 is limited to the period from the start of the lighting period of burst dimming until the rare gas fluorescent lamp 1 emits light over the entire axial direction, thereby improving the luminous efficiency. Can be kept to a minimum.

  In addition, if the magnitude of the switching element operation signal 103 is changed from the frequency increase period to the steady operation period discontinuously, the voltage waveform of the rare gas fluorescent lamp 1 may be disturbed and the discharge may become unstable. Accordingly, when the switching element operation signal 103 is shifted from the frequency increase period to the steady operation period, by providing the delay circuit 8 as shown in FIG. 2, the magnitude of the frequency continuously and gradually changes during the transition period. By doing so, the voltage can be supplied stably, the voltage waveform of the rare gas fluorescent lamp 1 is not disturbed, and it is possible to prevent the discharge from becoming unstable.

FIG. 6 shows on / off of the burst dimming signal 113, the switching element operation signal 103, and the switching elements Q1 and Q2 from the start of the burst dimming lighting period to the steady operation period through the frequency increase period and transition period. It is the figure which showed the operation waveform and lamp voltage waveform 112 showing a state.
The switching elements Q1 and Q2 are alternately turned on according to the operation of the switching element driving circuit 2 to which the switching element operation signal 103 is input. The polarity of the ramp voltage waveform 112 changes every time the switching element Q1 or Q2 is turned on, and a steep voltage change occurs. The period from the start of the lighting period of the burst dimming signal 113 until the rare gas fluorescent lamp 1 emits light in the entire axial direction is a frequency increasing period, the frequency of the switching element operation signal 103 is increased, and the lamp voltage waveform 112 The frequency at which a steep voltage change occurs also increases. Subsequently, during the transition period, the magnitude of the frequency of the switching element operation signal 103 changes gradually and continuously. In the steady operation period, the frequency of the switching element operation signal 103 returns to the steady frequency, and the frequency at which the steep voltage change of the ramp voltage waveform 112 returns to the steady state.

  As described above, in the rare gas fluorescent lamp lighting device according to the invention of the present embodiment, the switching element operation in the period from the start of the burst dimming period until the rare gas fluorescent lamp 1 emits light in the entire axial direction. The frequency of the signal 103 is increased, and the frequency of the switching element operation signal 103 is returned to a steady state after a transition period in which the frequency changes gradually and continuously from a high frequency state. As a result, the number of sharp voltage changes of the lamp voltage waveform 112 per unit time in the initial fixed period of the burst dimming period can be increased, and the spread of discharge can be accelerated. It is possible to suppress a delay in light emission at a location away from the light source, and to maintain the uniformity of the axial luminance distribution of the rare gas fluorescent lamp 1. Further, by suppressing the delay in light emission, the change in brightness due to the variation in the delay time is reduced, and flicker that occurs at a location away from the easily startable portion 15 can be suppressed. Further, since the frequency of the switching element operation signal 103 is gradually and continuously changed from a high period to a low period, the voltage waveform of the rare gas fluorescent lamp 1 is not disturbed and it is possible to prevent the discharge from becoming unstable. .

Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 7 is a diagram showing the configuration of a rare gas fluorescent lamp lighting device that performs burst dimming according to the invention of the present embodiment, and FIG. 8 shows the relationship between the duty ratio of the switching element operation signal 103 and the relative value of luminous efficiency. FIGS. 9A and 9B are diagrams showing the burst dimming signal 113, the switching element operation signal 103, the operation waveforms representing the on / off states of the switching elements Q1 and Q2, and the ramp voltage waveform 112. FIG.

Since the configuration of the rare gas fluorescent lamp 1 is the same as that of the first embodiment, description thereof is omitted.
In the rare gas fluorescent lamp lighting device, as shown in FIG. 7, the DC voltage supplied from the DC power supply 114 is converted into an AC high voltage by the inverter circuit 100 and supplied to the rare gas fluorescent lamp 1 as lighting power. The Further, the inverter circuit 100 intermittently operates in accordance with the burst dimming signal 113 to perform burst dimming. The inverter circuit 100 includes a step-up transformer 111, a switching element circuit 101, and an inverter control circuit 102. More specifically, the switching element circuit 101 includes a switching element Q1, a switching element Q2, and a switching element driving circuit 2. The inverter control circuit 102 includes a comparator 4, a comparison voltage control circuit 5, an oscillation circuit 6, a delay circuit 8, a timer circuit 9, and a switching element duty ratio increasing circuit 20.

  First, the inverter control circuit 102 will be described. The oscillation circuit 6 in the inverter control circuit 102 outputs an oscillation signal having a periodic sawtooth waveform. The sawtooth waveform voltage is inputted to the plus terminal of the comparator 4, and the comparison voltage from the comparison voltage control circuit 5 is inputted to the minus terminal. Is entered. Only when the drive signal having the sawtooth voltage exceeds the comparison voltage, the output voltage of the comparator 4 becomes High. That is, the switching element operation signal 103 that becomes the output voltage of the comparator 4 has a pulse waveform whose duty ratio changes depending on the magnitude of the comparison voltage. The duty ratio increases as the comparison voltage decreases, and decreases as the comparison voltage increases. Become.

  When the burst dimming signal 113 is High, the transistor in the comparison voltage control circuit 5 is in an OFF state, and the comparison voltage input to the minus terminal of the comparator 4 is Vref × R2 / (R1 + R2). This comparison voltage Vref × R2 / (R1 + R2) is smaller than the peak voltage of the sawtooth waveform that is the oscillation signal of the oscillation circuit 6. Therefore, the comparator 4 outputs the switching element operation signal 103 which is a pulse waveform having a duty ratio corresponding to the magnitude of the comparison voltage, and turns on the rare gas fluorescent lamp 1. When the burst dimming signal 113 is Low, the transistors in the comparison voltage control circuit 5 are turned on, and the comparison voltage is almost the same as Vref. Since the magnitude of Vref is set larger than the peak voltage of the sawtooth waveform that is the output signal of the oscillation circuit 6, the switching element operation signal 103 that is the pulse waveform output of the comparator 4 is stopped, and the rare gas fluorescent lamp 1 is Turns off.

  Further, the inverter control circuit 102 operates the timer circuit 9 for controlling the magnitude of the duty ratio increase period of the switching element operation signal 103, and changes the duty ratio of the switching element operation signal 103 from the end of the frequency increase period to the steady operation through the transition period. A delay circuit 8 for continuously changing the period, and a switching element duty ratio increasing circuit 20 for temporarily reducing the comparison voltage input to the comparator 4 and increasing the duty ratio of the switching element operation signal 103 are provided. The burst dimming signal 113 is input to the comparison voltage control circuit 5 and the timer circuit 9.

When the burst dimming signal 113 becomes High, the transistor in the comparison voltage control circuit 5 is turned off, and at the same time, the output of the timer circuit 9 becomes High. The capacitor of the delay circuit 8 is immediately charged, and the transistor of the switching element duty ratio increasing circuit 20 is turned on. As a result, the comparison voltage input to the negative terminal of the comparator 4 decreases, and the duty ratio of the switching element operation signal 103 increases. Next, when the set time of the timer circuit 9 elapses, the output of the timer circuit 9 becomes Low. The set time of the timer circuit 9 is a size obtained by experiments in advance for the time required from the lighting start time of the burst dimming to the time when the noble gas fluorescent lamp 1 emits light almost in the entire axial direction. When the output of the timer circuit 9 becomes Low, the capacitor voltage of the delay circuit 8 gradually decreases according to the time constant of the capacitor and the resistance, and the resistance between the collector and emitter of the transistor of the switching element duty ratio increasing circuit 20 gradually increases. The duty ratio decreases gradually and continuously. When the transistor is completely turned off, the comparison voltage becomes Vref × R2 / (R1 + R2), so that the duty ratio of the switching element operation signal 103 returns to a steady level. Thus, the transition period from the state in which the duty ratio of the switching element operation signal 103 increases to the time when it gradually decreases and returns to a steady magnitude is appropriately set according to the time constants of the capacitors and resistors constituting the delay circuit 8. .
Since the switching element circuit 101 and the step-up transformer 111 are the same as those in the first embodiment, description thereof is omitted.

  In the case of lighting with a rectangular wave voltage, the discharge component is not sufficiently formed at the stage immediately after lighting when the starting point of the discharge is generated at the easily startable portion 15, so that the capacitance component of the rare gas fluorescent lamp 1 is small and the lamp voltage. The waveform 112 has a large attenuation at the flat portion of the rectangular wave voltage waveform. However, by increasing the duty of the switching element operation signal 103 in the initial fixed period of the burst dimming period, the attenuation of the flat part of the lamp voltage waveform 112 is suppressed even when the discharge is not sufficiently formed. be able to. As a result, the magnitude of a steep voltage change when the polarity is switched can be ensured, and the lamp voltage waveform 112 capable of supplying sufficient energy to the rare gas fluorescent lamp 1 can be formed, so that the discharge spread can be accelerated. Can do.

  As a result, it is possible to suppress a delay in light emission at a location away from the easy-to-start portion 15 and maintain the uniformity of the axial luminance distribution of the rare gas fluorescent lamp 1. Further, by suppressing the delay in light emission, the change in brightness due to the variation in the delay time is reduced, and flicker that occurs at a location away from the easily startable portion 15 can be suppressed.

FIG. 8 is a diagram showing the relationship between the duty ratio of the switching element operation signal 103 and the relative value of the light emission efficiency.
As shown in the figure, the luminous efficiency is maximized when the duty ratio of the switching element operation signal 103 is 20%. Therefore, the steady operation is desirably performed at around 20%. When the duty ratio is increased, the duty ratio temporarily deviates from the high light emission efficiency. Therefore, if the increased duty ratio is continued longer than necessary, the overall light emission efficiency is lowered. Therefore, the increase period of the duty ratio of the switching element operation signal 103 is limited to the period from the start of the burst dimming lighting period until the rare gas fluorescent lamp 1 emits light in the entire axial direction. The reduction in efficiency can be minimized.

  In addition, when the change in the magnitude of the switching element operation signal 103 from the increasing period of the duty ratio to the steady operation period is performed discontinuously, the voltage waveform of the lamp voltage waveform 112 of the rare gas fluorescent lamp 1 is disturbed and the discharge is unstable. There is a risk of becoming. Therefore, when shifting from the increasing period of the duty ratio of the switching element operation signal 103 to the steady operation period, by providing the delay circuit 8 as shown in FIG. 7, the magnitude of the duty ratio is continuously moderated during the transition period. By changing to, the voltage can be supplied stably, the voltage waveform of the rare gas fluorescent lamp 1 is not disturbed, and the discharge can be prevented from becoming unstable.

FIG. 9 shows the ON state of the burst dimming signal 113, the switching element operation signal 103, the switching elements Q1 and Q2, from the start of the lighting period of burst dimming to the steady operation period through the duty ratio increasing period and transition period. It is the figure which showed the operation waveform and the lamp voltage waveform 112 showing the OFF state.
The switching elements Q1 and Q2 are alternately turned on according to the switching element operation signal 103. The polarity of the ramp voltage waveform 112 changes every time the switching element Q1 or Q2 is turned on, and a steep voltage change occurs. The period from the start of the lighting period of the burst dimming signal 113 until the rare gas fluorescent lamp 1 emits light substantially in the entire axial direction is a duty ratio increasing period, the duty ratio of the switching element operation signal 103 is increased, and the switching element Q1 , The on time of Q2 becomes longer, and the attenuation of the flat portion of the ramp voltage waveform 112 can be suppressed. Subsequently, during the transition period, the magnitude of the duty ratio of the switching element operation signal 103 changes gradually and continuously. In the steady operation period, the duty ratio of the switching element operation signal 103 returns to the steady duty ratio, but since the discharge spreads over the whole, the attenuation of the flat portion of the lamp voltage waveform 112 is small.

  As described above, in the rare gas fluorescent lamp lighting device according to the invention of the present embodiment, the switching element operation in the period from the start of the burst dimming period until the rare gas fluorescent lamp 1 emits light in the entire axial direction. The duty ratio of the signal 103 is increased, and the duty ratio of the switching element operation signal 103 is returned to a steady state through a transition period in which the duty ratio changes gradually and continuously from a high duty ratio state. Thus, since the lamp voltage waveform 112 that can supply sufficient energy to the rare gas fluorescent lamp 1 immediately after lighting can be formed, the spread of the discharge can be accelerated, so that the emission of light at a place away from the easily startable portion 15 can be achieved. The delay can be suppressed, and the uniformity of the axial luminance distribution of the rare gas fluorescent lamp 1 can be maintained. Further, by suppressing the delay in light emission, the change in brightness due to the variation in the delay time is reduced, and flicker that occurs at a location away from the easily startable portion 15 can be suppressed. Moreover, since the duty ratio of the switching element operation signal 103 is gradually and continuously changed from a high period to a low period, the voltage waveform of the rare gas fluorescent lamp 1 is not disturbed and the discharge can be prevented from becoming unstable. it can.

Next, a third embodiment of the present invention will be described with reference to FIGS.
FIG. 10 is a diagram showing a configuration of a rare gas fluorescent lamp lighting device that performs burst dimming according to the invention of this embodiment, and FIG. 11 shows burst dimming signal 113, switching element operation signal 103, and switching elements Q1 and Q2. FIG. 6 is a diagram showing an operation waveform and a ramp voltage waveform 112.

Since the configuration of the rare gas fluorescent lamp 1 is the same as that of the first embodiment, the description thereof is omitted.
In this rare gas fluorescent lamp lighting device, as shown in FIG. 10, the DC voltage supplied from the DC power supply 114 is converted into an AC high voltage by the inverter circuit 100 and supplied to the rare gas fluorescent lamp 1 as lighting power. Is done. Further, the inverter circuit 100 intermittently operates in accordance with the burst dimming signal 113 to perform burst dimming. The inverter circuit 100 includes a step-up transformer 111, a switching element circuit 101, and an inverter control circuit 102. More specifically, the switching element circuit 101 includes a switching element Q1, a switching element Q2, and a switching element driving circuit 2. The inverter control circuit 102 includes a comparator 4, a comparison voltage control circuit 5, an oscillation circuit 6, a frequency increase circuit 7, a delay circuit 8, a timer circuit 9, and a switching element duty ratio increase circuit 20.

  First, the inverter control circuit 102 will be described. The oscillation circuit 6 in the inverter control circuit 102 outputs an oscillation signal having a periodic sawtooth waveform. The sawtooth waveform voltage is inputted to the plus terminal of the comparator 4, and the comparison voltage from the comparison voltage control circuit 5 is inputted to the minus terminal. Is entered. Only when the drive signal having the sawtooth voltage exceeds the comparison voltage, the output voltage of the comparator 4 becomes High. The output voltage of the comparator 4, that is, the switching element operation signal 103 has a pulse waveform whose duty ratio changes depending on the magnitude of the comparison voltage. The duty ratio increases as the comparison voltage decreases, and decreases as the comparison voltage increases.

  When the burst dimming signal 113 is High, the transistor in the comparison voltage control circuit 5 is in an OFF state, and the comparison voltage input to the minus terminal of the comparator 4 is Vref × R2 / (R1 + R2). This comparison voltage Vref × R2 / (R1 + R2) is smaller than the peak voltage of the sawtooth waveform that is the oscillation signal of the oscillation circuit 6. Therefore, the comparator 4 outputs the switching element operation signal 103 which is a pulse waveform having a duty ratio corresponding to the magnitude of the comparison voltage, and the rare gas fluorescent lamp 1 is turned on. When the burst dimming signal 113 is Low, the transistors in the comparison voltage control circuit 5 are turned on, and the comparison voltage is almost the same as Vref. Since the magnitude of Vref is set larger than the peak voltage of the sawtooth waveform that is the output signal of the oscillation circuit 6, the switching element operation signal 103 that is the pulse waveform output of the comparator 4 is stopped, and the rare gas fluorescent lamp 1 is Turns off.

  Further, the inverter control circuit 102 makes the timer circuit 9 that controls the magnitude of the frequency increase period of the switching element operation signal 103, and the frequency and duty ratio of the switching element operation signal 103 to be steady through the transition period from the end of the frequency increase period. The delay circuit 8 for continuously changing to the operation period, the timing resistance of the oscillation circuit 6 are temporarily reduced, the frequency increase circuit 7 for increasing the frequency, and the comparison voltage input to the comparator 4 is temporarily And a switching element duty ratio increasing circuit 20 for increasing the duty ratio of the switching element operation signal 103. The frequency of the oscillation circuit 6 is determined by the size of the timing resistor RT and the timing capacitor CT, and the timing resistor RT and the oscillation frequency are in an inversely proportional relationship. The burst dimming signal 113 is input to the comparison voltage control circuit 5 and the timer circuit 9.

  When the burst dimming signal 113 becomes high, the transistor in the comparison voltage control circuit 5 is turned off, and at the same time, the output of the timer circuit 9 becomes high. The capacitor of the delay circuit 8 is immediately charged, and the transistor of the frequency increasing circuit 7 and the transistor of the switching element duty ratio increasing circuit 20 are turned on. As a result, the timing resistance of the oscillation circuit 6 becomes the magnitude of the parallel resistance of R4 and RT, and the operating frequency of the switching element operation signal 103 that is inversely proportional to the timing resistance value increases. Further, the comparison voltage input to the negative terminal of the comparator 4 decreases, and the duty ratio of the switching element operation signal 103 increases. Next, when the set time of the timer circuit 9 elapses, the output of the timer circuit 9 becomes Low. The set time of the timer circuit 9 is a size obtained by experiments in advance for the time required from the lighting start time of the burst dimming to the time when the rare gas fluorescent lamp 1 emits light almost in the entire axial direction. When the output of the timer circuit 9 becomes Low, the capacitor voltage of the delay circuit 8 gradually decreases in accordance with the time constant of the capacitor and the resistance, and the resistance between the collector and emitter of the transistors of the frequency increasing circuit 7 and the switching element duty ratio increasing circuit 20. Gradually increases, and the frequency and duty ratio continuously and gradually decrease. When each transistor is completely turned off, the timing resistance becomes RT and the comparison voltage becomes Vref × R2 / (R1 + R2), so that the operating frequency and the duty ratio of the switching element operation signal 103 return to a steady magnitude. As described above, the transition period from when the operating frequency and duty ratio of the switching element operation signal 103 are increased to when the switching element operation signal 103 gradually decreases and returns to a steady level is appropriately determined depending on the time constant of the capacitor and the resistor constituting the delay circuit 8. Is set.

  Since the switching element circuit 101 and the step-up transformer 111 are the same as those in the first embodiment, description thereof will be omitted. In addition, when the frequency of the switching element operation signal 103 and the magnitude of the duty ratio increase period are discontinuously changed, the voltage waveform of the lamp voltage waveform 112 of the rare gas fluorescent lamp 1 is disturbed and discharge occurs. May become unstable. Accordingly, when shifting from the increase period of the frequency and duty ratio of the switching element operation signal 103 to the steady operation period, by providing the delay circuit 8 as shown in FIG. 10, the magnitude of the frequency and duty ratio can be increased during the transition period. By continuously and gently changing the voltage, the voltage can be stably supplied, and the voltage waveform of the rare gas fluorescent lamp 1 can be prevented from being disturbed and the discharge can be prevented from becoming unstable.

In the invention of this embodiment, by increasing both the frequency and the duty ratio of the switching element operation signal 103 from the start of the lighting period of burst dimming until the rare gas fluorescent lamp 1 emits light over substantially the entire axial direction. The effects of the first and second embodiments can be shared and higher effects can be obtained.
That is, the number of discharge cycles per unit time is increased by increasing the frequency of the switching element operation signal 103 in the period from the start of the lighting period of burst dimming until the rare gas fluorescent lamp 1 emits light over the entire axial direction. And the spread of the discharge can be accelerated. Furthermore, by increasing the duty of the switching element operation signal 103 in the period from the start of the burst dimming lighting period until the rare gas fluorescent lamp 1 emits light in the entire axial direction, it is sufficient for the rare gas fluorescent lamp 1. Since the ramp voltage waveform 112 capable of supplying energy can be formed, the spread of discharge can be accelerated.

  As a result, it is possible to suppress a delay in light emission at a location away from the easy-to-start portion 15 and maintain the uniformity of the axial luminance distribution of the rare gas fluorescent lamp 1. Further, by suppressing the delay of the light emission, the change in brightness due to the variation in the delay time is reduced, and the flicker that occurs at a location away from the easy-start portion 15 can be suppressed.

FIG. 11 shows the burst dimming signal, the switching element operation signal 103, the operation waveforms of the switching elements Q1 and Q2, the lamp voltage, from the start of the burst dimming period to the steady operation period through the frequency increase period and transition period. FIG. 6 is a diagram showing a waveform 112;
The switching elements Q1 and Q2 are alternately turned on according to the switching element operation signal 103. The polarity of the ramp voltage waveform 112 changes every time the switching element Q1 or Q2 is turned on, and a steep voltage change occurs. The period from the start of the burst dimming period until the rare gas fluorescent lamp 1 emits light in the entire axial direction is a frequency increase period and a duty ratio increase period, and the frequency and duty ratio of the switching element operation signal 103 are increased. Increases, the frequency at which the steep voltage change of the ramp voltage waveform 112 occurs is increased, and the attenuation of the flat portion of the ramp voltage waveform 112 can be suppressed. Subsequently, during a transition period, the frequency of the switching element operation signal 103 and the magnitude of the duty ratio change gradually and continuously. In the steady operation period, the frequency and duty ratio of the switching element operation signal 103 return to a steady magnitude, and the lamp voltage waveform 112 also shows a voltage change during the steady operation.

As described above, in the rare gas fluorescent lamp lighting device according to the invention of this embodiment, switching is performed during the period from the start of the lighting period of the burst dimming signal 113 until the rare gas fluorescent lamp 1 emits light over the entire axial direction. The frequency and duty ratio of the element operation signal 103 are increased, and the frequency and duty ratio of the switching element operation signal 103 are made steady through a transition period in which the frequency and duty ratio change gradually and continuously from a high frequency state and a high duty ratio state. Return to.
As a result, the number of sharp voltage changes per unit time is increased, and the lamp voltage waveform 112 capable of supplying sufficient energy to the rare gas fluorescent lamp 1 can be formed even immediately after lighting, thereby speeding up the spread of discharge. Thus, a delay in light emission at a location away from the easy-to-start site 15 is suppressed, and the uniformity of the axial luminance distribution of the rare gas fluorescent lamp 1 can be maintained. Further, by suppressing the delay of the light emission, the change in brightness due to the variation in the delay time is reduced, and the flicker that occurs at a location away from the easy-start portion 15 can be suppressed. In addition, since the frequency and duty ratio of the switching element operation signal 103 are gradually and continuously changed from a high period to a low period, the voltage waveform of the rare gas fluorescent lamp 1 is not disturbed and discharge is prevented from becoming unstable. be able to.

  Next, experimental results of the rare gas fluorescent lamp lighting device according to the invention of the first to third embodiments are shown in FIGS.

  The rare gas fluorescent lamp lighting device was lit by connecting four rare gas fluorescent lamps in parallel. The rare gas fluorescent lamp has a tube diameter of 8.0 mm, a total length of 500 mm, and an enclosed gas Xe160 Torr. By applying a conductive material to the inside of the rare gas fluorescent lamp, the easy start site 15 is arranged on one side of the end of the rare gas fluorescent lamp. Provided on one side. The frequency of the switching element operation signal was 100 kHz, and the duty ratio of the switching element operation signal was 20%. The frequency of burst dimming was 100 Hz. While changing the duty ratio of burst dimming (lighting period of burst dimming / period of burst dimming), the luminance in the vicinity of the end portion on the side where the easily startable portion is arranged (hereinafter referred to as measurement point A), The brightness at the measurement point B / the brightness at the measurement point A when measuring the brightness near the end opposite to the side where the easy-to-start site 15 is arranged (hereinafter referred to as measurement point B), and the burst level. The relationship of the light duty ratio is shown in FIG. Further, FIG. 13 shows the presence or absence of flicker and the magnitude of the delay time from when the measurement point A emits light until the measurement point B emits light when the duty ratio of burst dimming is changed.

  When the duty ratio of burst dimming was 10%, the luminance at the measurement point B decreased to 70% with respect to the luminance at the measurement point A. Further, as shown in FIG. 13, the duty ratio of the burst dimming is about 40%, and flickering occurs near the measurement point B. Further, the delay time from the measurement point A emitting light to the measurement point B emitting light was 200 to 400 us.

  Next, the switching element operation signal 103 was lit for a period of increasing frequency at the beginning of the burst dimming lighting period. The frequency of the switching element operation signal 103 during the increase period is 200 kHz, the increase period is 100 μs, and the transition period is 100 μs. As a result of measuring the luminance at the measurement point A and the luminance at the measurement point B while changing the duty ratio of burst dimming, as shown in FIG. 12, when the duty ratio of burst dimming is 10%, the measurement point B Was maintained at 80% of the luminance at the measurement point A. Further, as a result of confirming the presence or absence of flickering, as shown in FIG. 13, flickering did not occur when the duty ratio of burst dimming was 30% or more. Further, the delay time from when the measurement point A emitted light to when the measurement point B emitted light was 130 to 270 us.

  Subsequently, at the initial stage of the burst dimming period, the switching element operation signal 103 was lit with an increase period of the duty ratio. The duty ratio of the switching element operation signal 103 during the increase period is 80%, the increase period is 100 μs, and the transition period is 100 μs. As a result of measuring the luminance at the measurement point A and the luminance at the measurement point B while changing the duty ratio of burst dimming, as shown in FIG. 12, when the duty ratio of burst dimming is 10%, the measurement point B Was maintained at 82% of the luminance at the measurement point A. Further, as a result of confirming the presence or absence of flickering, as shown in FIG. 13, flickering did not occur when the duty ratio of burst dimming was 30% or more. Further, the delay time from the measurement point A emitting light to the measurement point B emitting light was 120 to 240 us.

  Subsequently, in the initial stage of the burst dimming period, the switching element operation signal 103 was lit with an increase period of the frequency and duty ratio. The frequency of the switching element operation signal 103 during the increase period is 200 kHz, the duty ratio is 80%, the increase period is 100 μs, and the transition period is 100 μs. As a result of measuring the luminance at the measurement point A and the luminance at the measurement point B while changing the duty ratio of burst dimming, as shown in FIG. 12, when the duty ratio of burst dimming is 10%, the measurement point B Was maintained at 93% of the luminance at the measurement point A. Further, as a result of confirming the presence or absence of flicker, as shown in FIG. 13, flicker did not occur even when the duty ratio of burst dimming was 10%. Further, the delay time from the measurement point A emitting light to the measurement point B emitting light was 50 to 90 us.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.
According to the rare gas fluorescent lamp lighting device of the first to third embodiments of the present invention, flicker is prevented, but a high surge is caused by the high lamp impedance at the start of the lighting period of burst dimming. It has been found that there is a risk that a voltage may be generated, resulting in creeping discharge between electrodes outside the discharge space, and dielectric breakdown of connectors, wiring, etc.
Therefore, in the fourth embodiment of the present invention, the frequency of the switching element operation signal is suddenly increased or suddenly switched in the “period from the start of the lighting period until light is emitted in the entire lamp axis direction” of burst dimming. By increasing the frequency stepwise (gradual increase) or increasing the duty ratio stepwise (gradual increase) without increasing the duty ratio of the element operation signal, overvoltage input is suppressed, and the luminance distribution is uneven or flickering. However, in addition to the improvement, it becomes a rare gas fluorescent lamp lighting device that is excellent in safety.

FIG. 15 is a diagram showing detailed lamp voltage waveforms from the frequency increase period shown in FIG. 6 to the steady operation period. In the figure, the transition period shown in FIG. 6 is not provided.
In the figure, the period from the lighting start time to the completion of all emission is the frequency increase period, and the period after the completion of all emission is the steady operation period. The lamp voltage during the frequency increase period generates a surge voltage that is generally higher than that during the steady operation period. Among them, in particular, the surge voltage immediately after the lighting start point is remarkably higher than those in other periods (portion surrounded by circles in FIG. 15).
The reason why the surge voltage increases immediately after the lighting start time is increased immediately after the lighting start time because the power supply capability from the lighting circuit to the lamp increases due to the frequency increase. On the other hand, since the discharge of the rare gas fluorescent lamp has not yet been formed, the impedance of the lamp is equivalent to a capacitor having a small capacitance, and a resonant circuit having a high Q is formed between the leakage inductance of the transformer. it is conceivable that.
The presence of this high surge voltage may degrade insulating materials such as transformers, connectors, and wiring, and may cause a short life of the device.
Note that at the start of lighting and at the time of completion of all light emission, a wide range of light emission is taken with a high-speed video camera, and the light output at a plurality of locations in the lamp axis direction is simultaneously measured with a light sensor, and the time change of those outputs is measured. Detection can be confirmed by measurement.

FIG. 16 is a diagram showing a configuration of a rare gas fluorescent lamp lighting device that performs burst dimming according to the invention of the present embodiment.
In the figure, an inverter circuit 100 converts a DC voltage from a DC power source 114 into a high frequency high voltage and applies it to the rare gas fluorescent lamp 1. The inverter circuit 100 has a function of performing burst dimming according to a burst dimming signal from the outside (for example, a dimming control circuit of a liquid crystal television).
The inverter circuit 100 includes a switching element circuit 101, a step-up transformer 111, and an inverter control circuit 102. The switching element circuit 101 is configured by a push-pull circuit method, a half-bridge circuit method, a full-bridge circuit method, and the like, and converts a DC voltage supplied from the DC power supply 114 into a high-frequency voltage and outputs it. The step-up transformer 111 boosts the high-frequency voltage supplied from the switching element circuit 101 and outputs it as a high-frequency high voltage. The high frequency high voltage output from the step-up transformer 111 is input to the rare gas fluorescent lamp 1.
The inverter control circuit 102 outputs a switching element operation signal 103 for controlling the switching elements Q1 and Q2 of the switching element circuit 101 to the switching element circuit 101, and performs burst dimming control according to the burst dimming signal 113 from the outside. The function to perform. The inverter control circuit 102 includes a switching element operation signal generation circuit 115 and a cycle / on time control circuit 116.

The period / on time control circuit 116 receives the burst dimming signal and outputs an on time control signal 117 and a period control signal 118 to the switching element operation signal generation circuit 115.
The on-time control signal 117 represents the magnitude of the on-time of the switching element operation signal 103, and the period control signal 118 represents the magnitude of the period of the switching element operation signal 103. The magnitudes of the on-time control signal 117 and the period control signal 118 are stored in the circuit, and the magnitude can be changed for each set time based on the burst dimming signal.
The switching element operation signal generation circuit 115 receives the burst dimming signal 113, the on-time control signal 117, and the cycle control signal 118 and outputs the switching element operation signal 103. The switching element operation signal 103 is a pulse signal whose period is the magnitude of the period control signal 118 and whose on-time is the magnitude of the on-time control signal 117.
Further, the output and stop of the switching element operation signal 103 are controlled according to the burst dimming signal 113.

17A and 17B show the ON / OFF states of the switching element operation signal 103 and the switching elements Q1 and Q2 in the initial period of the burst dimming in the rare gas fluorescent lamp lighting device shown in FIG. It is a figure which shows the operation waveform and lamp voltage waveform which were performed.
FIG. 17A shows a waveform when the switching element operation signal 103 is operated at a higher frequency from the lighting start time of burst dimming, and FIG. 17B shows the waveform from the lighting start time of burst dimming. The waveform when the frequency of the switching element operation signal 103 is gradually increased is shown.
In the case of FIG. 17A, a high surge voltage exceeding a predetermined voltage is generated in the lamp voltage waveform immediately after the lighting start time. On the other hand, in the case of FIG. 17B, it can be seen that a high surge voltage exceeding a predetermined voltage is not generated and the surge voltage is suppressed. Here, the predetermined voltage is, for example, 2 kV.

FIGS. 18A and 18B show the ON / OFF states of the switching element operation signal 103 and the switching elements Q1 and Q2 in the initial period of the burst dimming in the rare gas fluorescent lamp lighting device shown in FIG. It is a figure which shows the operation waveform and lamp voltage waveform which were performed.
FIG. 18A shows a waveform when the duty ratio of the switching element operation signal 103 is increased from the lighting start time of burst dimming, and FIG. 18B shows the lighting start time of burst dimming. The waveform when operating by gradually increasing the duty ratio of the switching element operation signal 103 is shown.
In the case of FIG. 18A, a high surge voltage exceeding a predetermined voltage is generated in the lamp voltage waveform immediately after the lighting start time. On the other hand, in the case of FIG. 18B, it can be seen that a high surge voltage exceeding a predetermined voltage is not generated, and the surge voltage is suppressed.

FIGS. 19A and 19B show the on / off states of the switching element operation signal 103 and the switching elements Q1 and Q2 at the beginning of the lighting period of burst dimming in the rare gas fluorescent lamp lighting device shown in FIG. It is a figure which shows the operation waveform and lamp voltage waveform which were performed.
FIG. 19A shows a waveform when the switching element operation signal 103 is operated at a high frequency and duty ratio from the start of burst dimming, and FIG. 18B shows the burst dimming. The waveform when the frequency and duty ratio of the switching element operation signal 103 are gradually increased from the start time is shown.
In the case of FIG. 19A, the lamp voltage waveform immediately after the lighting start time has a high surge voltage exceeding a predetermined voltage. On the other hand, in the case of FIG. 19B, it can be seen that a high surge voltage exceeding a predetermined voltage is not generated, and the surge voltage is suppressed.

  20 (a), (b), (c), (d), (e), and (f) show the magnitude of the frequency and / or duty ratio of the switching element operation signal 103 in the entire lighting period of burst dimming. It is a schematic diagram showing the time change of length.

FIG. 20A shows the frequency and / or the duty ratio of the switching element operation signal 103 from the start time of the lighting period (lighting start time) to the time when the entire rare gas fluorescent lamp emits light (all light emission completion time). It is a schematic diagram when the height is higher than the size of the steady operation and a constant size.
By operating in this way, the time from the lighting start time to the completion of all light emission is shortened, so that there is an effect of improving the uniformity of the luminance distribution and suppressing flickering. The frequency and / or duty ratio of the switching element operation signal 103 is returned to the level of the steady operation as shown in FIG. 20 (e) even before the completion of all the light emission and in FIG. 20 (f). As shown, the above-described effect can be obtained even after the completion of all emission. However, since the light emission efficiency deteriorates after the completion of all the light emission, it is desirable to quickly return to the level of the steady operation at the time of the completion of all the light emission.

FIG. 20B shows that the frequency and / or duty ratio of the switching element operation signal 103 is higher than the steady operation and constant from the lighting start time to the completion of all emission. FIG. 12 is a schematic diagram when the frequency and / or duty ratio of the operation signal 103 is continuously changed when returning to the normal operation, and in the case of FIGS. 6, 9, and 11. Corresponds to operating conditions.
When the frequency of the switching element operation signal 103 and / or the magnitude of the duty ratio are suddenly changed, there is a problem that the switching element operation signal 103 is disturbed as shown in FIG. 21, but it is continuously changed as described above. Thus, the disturbance of the switching element operation signal 103 can be prevented.
This problem can also be avoided by a method in which the inverter control circuit is configured by a digital circuit and performs synchronous control, but the above method is effective when configured by an analog circuit.

FIGS. 20C and 20D show the period and / or duty ratio of the switching element operation signal 103 in a period from the lighting start time to the completion of all light emission, and at least a fixed period reaching the completion time of all light emission. The frequency of the switching element operation signal 103 is gradually increased during the period up to the certain period, that is, at the beginning of the certain period. FIG.
By gradually increasing the frequency and / or the duty ratio of the switching element operation signal 103 until the predetermined period, the generation of a remarkably high surge voltage immediately after the start of lighting as shown in FIG. 15 is suppressed. can do.
The schematic diagram of FIG. 20C shows a case where the frequency and / or the duty ratio of the switching element operation signal 103 at the start of lighting is larger than the magnitude at the steady state, and the schematic diagram of FIG. Although the figure shows a small case, the same effect can be obtained in either case.

FIG. 22 is a block diagram showing a specific configuration in the inverter control circuit 102 of the rare gas fluorescent lamp lighting device shown in FIG. 16, and FIG. 23 is a timing chart showing signal waveforms of respective parts in the inverter control circuit 102.
The inverter control circuit 102 includes a switching element operation signal generation circuit 115 and a cycle / on time control circuit 116. The switching element operation signal generation circuit 115 receives the burst dimming PWM signal 113, the cycle control signal 117, and the on-time control signal 118, and outputs the switching element operation signal 103. The period / on time control circuit 116 receives the burst dimming PWM signal 113 and outputs a period control signal 118 and an on time control signal 117.
The switching element operation signal generation circuit 115 includes a counter circuit (1) 119 and a comparison circuit 120. The counter circuit (1) 119 receives the burst dimming PWM signal 113 and the cycle control signal 117, and receives a count signal. 1 is output. The comparison circuit 120 receives the count signal 1 and the on-time control signal 118 and outputs the switching element operation signal 103.
The cycle / on-time control circuit 116 includes a counter circuit (2) 121 and a cycle / on-time control signal generation circuit 122. The counter circuit (2) 121 receives the burst dimming PWM signal 113 and counts it. Signal 2 is output.
Here, the burst dimming PWM signal 113 and the switching element operation signal 103 are binary logic signals, and the count signal 1, the count signal 2, the cycle control signal 117, and the on-time control signal 118 are integer signals.

Next, the operation of the switching element operation signal generation circuit 115 will be described.
When the burst dimming PWM signal 113 changes from Low to High, the counter circuit (1) 119 starts counting. The count signal 1 starts from a magnitude 1 and increases by 1 at certain time intervals. When the count signal 1 reaches the magnitude of the cycle control signal 118, the counter circuit (1) 119 returns to 1 and repeats the same operation.
The comparison circuit 120 compares the count signal 1 with the on-time control signal 118. When the count signal 1 ≦ the on-time control signal 118, the switching element operation signal 103 is set to High, and the count signal 1> the on-time control signal 118. In this case, the switching element operation signal 103 is set to Low.
In other words, the cycle of the switching element operation signal 103 is “the time when the magnitude of the count signal 1 increases by 1” × “the magnitude of the cycle control signal 117”, and the on-time (high level time) of the switching element operation signal 103 ) Is “the time during which the magnitude of the count signal 1 increases by 1” × “the magnitude of the on-time control signal 118”.
When the burst dimming PWM signal 113 changes from High to Low, the counter circuit (1) 119 stops counting when the count signal 1 reaches the magnitude of the cycle control signal 117, and the count signal 1 is cycle controlled. The magnitude of the signal 117 is maintained. That is, the switching element operation signal 103 maintains the low level.

Next, the operation of the period / on time control circuit 116 will be described.
When the burst dimming PWM signal 113 changes from Low to High, the counter circuit (2) 121 starts counting. The counter circuit (2) 121 operates in synchronization with the counter circuit (1) 119. The count signal 2 starts from the magnitude 1 and increases by 1 at certain time intervals. When the magnitude reaches the maximum countable value Q _MAX , the count operation is stopped and Q _MAX is maintained.
The period / on time control circuit 116 compares the magnitude of the count signal 2 with the integers τ ₁ , τ ₂ , τ ₃ ,... Τ _n stored in the circuit, and associates them with the result. The two stored integer signals are output as a period control signal 117 and an on-time control signal 118.
Specifically, when the count signal 2 is Q, the period control signal 117 is C, and the on-time control signal 118 is D, when 0 ≦ Q <τ ₁ , C = T ₀ , D = Ton ₀ , and τ ₁ When ≦ Q <τ ₂ , C = T ₁ and D = Ton ₁ , and when τ _n ≦ Q, C = T _n and D = Ton _n .
When the burst dimming PWM signal 113 changes from High to Low, the count signal 2 changes to 0 and maintains its magnitude.
Period of the thus switching element operating signal 103, the time change of the ON time is an integer signal _{τ 1 ~τ n, T 0 ~T} n, Ton 0 ~Ton n of be arbitrarily changed by adjusting the size Can do.
In the inverter control circuit 102 shown in FIG. 22, the duty ratio of the switching element operation signal 103 is expressed as “the magnitude of the on-time control signal” / “the magnitude of the periodic control signal” because of the ease of circuit configuration. Although the control is performed by replacing, naturally, this is equivalent to controlling the duty ratio and is not different from the gist of the invention.

Next, the circuit operation of the inverter control circuit 102 shown in FIG. 22 will be described with reference to the timing chart shown in FIG.
Here, as shown in FIG. 23, τ ₁ = 80, τ ₂ = 400, T ₀ = 8, T ₂ = 10, Ton ₀ = 2, Ton _n = 4, and Ton _n = 2.
When the burst dimming PWM signal 113 changes from Low to High, the count signal 1 and the count signal 2 become 1 and increase by 1 at regular intervals. In this example, the count-up cycle of the count signal 1 and the count signal 2 is the same, but the cycle of the count signal 2 may be n times that of the count signal 1.

While the count signal 2 is between 0 and τ ₁ (= 80), the cycle control signal 117 is 8 and the on-time control signal 118 is 2. The switching element operation signal 103 becomes High when the count signal 1 ≦ the on-time control signal 118 (= 2), and becomes Low otherwise. The count signal 1 returns to 1 when the period control signal 117 becomes 8 and repeats the same operation.
When the count signal 2 becomes τ ₁ = 80, the cycle control signal 117 changes to 5 and the on-time control signal 118 changes to 4. The switching element operation signal 103 becomes High when the count signal 1 ≦ the on-time control signal 118 (= 4), and becomes Low otherwise. The count signal 1 returns to 1 when the period control signal 117 becomes 5 and repeats the same operation.
When the count signal 2 becomes τ ₂ = 400, the period control signal 117 changes to 10 and the on-time control signal 118 changes to 2. The switching element operation signal 103 becomes High when the count signal 1 ≦ the on-time control signal 118 (= 2), and becomes Low otherwise. The count signal 1 returns to 1 when the period control signal 117 becomes 10 and repeats the same operation.
When the count signal 2 reaches the maximum countable value Q _MAX , the size of Q _MAX is maintained.
When the burst dimming PWM signal 113 becomes Low, the count signal stops counting when the period control signal 117 reaches 1 and the count signal 2 is reset to 0 at the same time.

  In each of the above embodiments, the frequency increase period, the duty ratio increase period, and the frequency and duty ratio increase period are not fixed in advance, but the output of the optical sensor disposed at a location corresponding to B in FIG. Thus, feedback control may be performed so as to determine the completion point of all light emission.

24 is a cross-sectional view perpendicular to the tube axis of a straight tubular rare gas fluorescent lamp 123 applied to each embodiment of the present invention and having a structure different from that of the rare gas fluorescent lamp shown in FIG. 3 (see Special Table 2004-510302). ).
As shown in the figure, two linear internal electrodes 125 and 126 arranged in the tube axis direction along the inner wall of the glass tube 124 are covered with dielectrics 127 and 128 made of glass, and the inner wall of the glass tube 124 and A fluorescent material 129 is formed on the dielectrics 127 and 128. As described above, the rare gas fluorescent lamp according to each embodiment of the present invention includes not only the rare gas fluorescent lamp provided with the external electrode extending in the tube axis direction on the outer surface of the glass tube shown in FIG. A rare gas fluorescent lamp in which internal electrodes 125 and 126 are arranged in the tube axis direction along the inner wall of the glass tube 124 as shown is also applicable. The rare gas fluorescent lamp having the structure shown in FIGS. 3 and 24 is a lamp belonging to the category of dielectric barrier discharge lamps that discharge via a dielectric.

  Further, although the lighting device of the present invention has been described in this specification for a rare gas fluorescent lamp, in terms of maintaining the uniformity of the radiance distribution and preventing a high surge voltage, the lighting device of the present invention is fluorescent. It is not limited to lamps. 3 and FIG. 24, and other discharge lamps that use excimer light generated by discharge by generating discharge in the discharge container via at least one dielectric between the electrode and the discharge container. Then, the technique described in this application can be applied to these lamps. Further, the application is not limited to the liquid crystal backlight or the illumination application.

It is a figure which shows the basic composition of the noble gas fluorescent lamp lighting device which performs burst light control which concerns on this invention. It is a figure which shows the structure of the noble gas fluorescent lamp lighting device which performs burst light control which concerns on invention of 1st Embodiment. It is a figure which shows the structure of the noble gas fluorescent lamp shown in FIG. It is a figure which shows the structure which used the noble gas fluorescent lamp shown in FIG. 2 as a backlight of a liquid crystal panel. It is a figure which shows the relationship between the frequency of a switching element operation signal, and luminous efficiency relative value. It is a figure which shows the burst dimming signal in the invention of 1st Embodiment, the switching element operation signal, the operation waveform of a switching element, and a lamp voltage waveform. It is a figure which shows the structure of the noble gas fluorescent lamp lighting device which performs burst light control which concerns on invention of 2nd Embodiment. It is a figure which shows the relationship between the duty ratio of a switching element operation signal, and luminous efficiency relative value. It is a figure which shows the burst dimming signal in the invention of 2nd Embodiment, the switching element operation signal, the operation waveform of a switching element, and a lamp voltage waveform. It is a figure which shows the structure of the noble gas fluorescent lamp lighting device which performs burst light control which concerns on invention of 3rd Embodiment. It is a figure which shows the burst dimming signal in the invention of 3rd Embodiment, the switching element operation signal, the operation waveform of a switching element, and a lamp voltage waveform. It is a figure which shows the experimental result of the noble gas fluorescent lamp lighting device which concerns on invention of 1st thru | or 3rd embodiment. It is a figure which shows the experimental result of the noble gas fluorescent lamp lighting device which concerns on invention of 1st thru | or 3rd embodiment. It is a figure which shows the structure of the noble gas fluorescent lamp which performs burst light control which concerns on a prior art, the burst light control signal which concerns on a prior art, the light output of the measurement point A, and the light output of the measurement point B. FIG. 7 is a diagram showing a detailed ramp voltage waveform from the frequency increase period shown in FIG. 6 to the steady operation period. It is a figure which shows the structure of the noble gas fluorescent lamp lighting device which performs burst light control which concerns on invention of 4th Embodiment. The noble gas fluorescent lamp lighting device shown in FIG. 16 has an inverter circuit that applies an alternating high voltage to the electrode during the lighting period of burst dimming, and the initial switching element operation signal and the on / off state of the switching element It is a figure which shows the operation | movement waveform and lamp voltage waveform which represented. FIG. 17 is a diagram showing a switching element operation signal at the beginning of the lighting period of burst dimming, an operation waveform representing an on / off state of the switching element, and a lamp voltage waveform in the rare gas fluorescent lamp lighting device shown in FIG. 16. FIG. 17 is a diagram showing a switching element operation signal at the beginning of the lighting period of burst dimming, an operation waveform representing an on / off state of the switching element, and a lamp voltage waveform in the rare gas fluorescent lamp lighting device shown in FIG. 16. It is the schematic diagram showing the time change of the magnitude | size of the frequency and / or duty ratio of a switching element operation signal in the whole lighting period of burst light control. It is a figure for demonstrating the problem that the switching element operation signal 103 will be disturb | confused when the magnitude | size of the frequency and / or duty ratio of a switching element operation signal is changed abruptly. It is a block diagram which shows the specific structure in the inverter control circuit 102 of the noble gas fluorescent lamp lighting device shown in FIG. 3 is a timing chart showing signal waveforms at various parts in the inverter control circuit 102. FIG. 4 is a cross-sectional view perpendicular to the tube axis of a straight tubular rare gas fluorescent lamp 123 applied to each embodiment of the present invention and having a structure different from that of the rare gas fluorescent lamp shown in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Noble gas fluorescent lamp 2 Switching element drive circuit 3 Push pull operation circuit 4 Comparator 5 Comparison voltage control circuit 6 Oscillation circuit 7 Frequency increase circuit 8 Delay circuit 9 Timer circuit 11 Glass tube 12, 13 External electrode 14 Fluorescent substance 15 Easy start part 16 Liquid crystal panel 17 Optical film 18 Diffuser 19 Case 20 Switching element duty ratio increasing circuit 100 Inverter circuit 101 Switching element circuit 102 Inverter control circuit 103 Switching element operation signal 110 Output signal 111 Step-up transformer 112 Lamp voltage waveform 113 Burst dimming signal 114 DC power supply 115 Switching element operation signal generation circuit 116 Period / on time control circuit 117 On time control signal 118 Period control signal 119 Counter circuit (1)
120 comparison circuit 121 counter circuit (2)
122 period / on-time control signal generation circuit 123 rare gas fluorescent lamp 124 glass tube 125, 126 internal electrode 127, 128 dielectric 129 fluorescent material Q1, Q2 inverter switching element

Claims (8)

One or more rare gases of He, Ar, Xe, and Kr are sealed inside the glass tube, a phosphor is applied to the inner surface of the glass tube, and an electrode extending in the axial direction of the glass tube is disposed. A rare gas fluorescent lamp, and an inverter circuit for applying an alternating high voltage to the electrode, the inverter circuit turning on the switching element in accordance with the inverter control circuit for outputting a switching element operation signal, A switching element circuit that converts a DC voltage to an AC voltage by controlling off and a step-up transformer that boosts the AC voltage from the switching element circuit, and periodically turns on and off the rare gas fluorescent lamp. In the rare gas fluorescent lamp lighting device that performs burst dimming by controlling the time ratio between the lighting period and the lighting period,
The frequency of the switching element operation signal in at least a part of the period from the start of lighting of burst dimming to the completion of all light emission in which the rare gas fluorescent lamp emits light substantially in the entire axial direction is set at the steady state. A rare gas fluorescent lamp lighting device characterized by having a frequency higher than that of a switching element operation signal.   2. The rare gas fluorescent lamp lighting device according to claim 1, wherein the frequency of the switching element operation signal is gradually increased at an initial stage of the at least part of the period.   From the frequency of the switching element operation signal in at least a part of the period from the start of lighting of the burst dimming to the completion of the total light emission in which the rare gas fluorescent lamp emits light substantially in the entire axial direction, The rare gas fluorescent lamp lighting device according to claim 1 or 2, wherein the frequency of the switching element operation signal is continuously changed when returning to the frequency of the switching element operation signal. One or more rare gases of He, Ar, Xe, and Kr are sealed inside the glass tube, a phosphor is applied to the inner surface of the glass tube, and an electrode extending in the axial direction of the glass tube is disposed. A rare gas fluorescent lamp, and an inverter circuit for applying an alternating high voltage to the electrode, the inverter circuit turning on the switching element in accordance with the inverter control circuit for outputting a switching element operation signal, A switching element circuit that converts a DC voltage to an AC voltage by controlling off and a step-up transformer that boosts the AC voltage from the switching element circuit, and periodically turns on and off the rare gas fluorescent lamp. In the rare gas fluorescent lamp lighting device that performs burst dimming by controlling the time ratio between the lighting period and the lighting period,
The duty ratio of the switching element operation signal in at least a part of the period from the start of lighting of burst dimming to the completion of all emission in which the rare gas fluorescent lamp emits light in the entire axial direction is A rare gas fluorescent lamp lighting device characterized by having a duty ratio higher than that of the switching element operation signal.   5. The rare gas fluorescent lamp lighting device according to claim 4, wherein a duty ratio of the switching element operation signal is gradually increased at an early stage of the at least a part of the period.   From the duty ratio of the switching element operation signal during at least a part of the period from the start of lighting of the burst dimming to the completion of the total emission in which the rare gas fluorescent lamp emits light in the entire axial direction. 6. The rare gas fluorescent lamp lighting according to claim 4, wherein when returning to the duty ratio of the normal switching element operation signal, the duty ratio of the switching element operation signal is continuously changed. apparatus. One or more rare gases of He, Ar, Xe, and Kr are sealed inside the glass tube, a phosphor is applied to the inner surface of the glass tube, and an electrode extending in the axial direction of the glass tube is disposed. A rare gas fluorescent lamp, and an inverter circuit for applying an alternating high voltage to the electrode, the inverter circuit turning on the switching element in accordance with the inverter control circuit for outputting a switching element operation signal, A switching element circuit that converts a DC voltage to an AC voltage by controlling off and a step-up transformer that boosts the AC voltage from the switching element circuit, and periodically turns on and off the rare gas fluorescent lamp. In the rare gas fluorescent lamp lighting device that performs burst dimming by controlling the time ratio between the lighting period and the lighting period,
The frequency and duty ratio of the switching element operation signal in at least a part of the period from the start of lighting of burst dimming to the completion of all emission in which the rare gas fluorescent lamp emits light in the entire axial direction are determined. A rare gas fluorescent lamp lighting device characterized in that it is higher than the frequency and duty ratio of the switching element operation signal at all times.   From the frequency and duty ratio of the switching element operation signal in at least a part of the period from the lighting start time of the burst dimming to the completion time of the total emission in which the rare gas fluorescent lamp emits light substantially in the entire axial direction, 8. The rare gas fluorescence according to claim 7, wherein when returning to the frequency and duty ratio of the switching element operation signal in the steady state, the frequency and duty ratio of the switching element operation signal are continuously changed. Lamp lighting device.

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